Python 3.8.6rc1 (tags/v3.8.6rc1:08bd63d, Sep  7 2020, 22:55:24) [MSC v.1927 32 bit (Intel)] on win32
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>>> a="gaozhihao is caigou"
>>> b=list(a)
>>> b
['g', 'a', 'o', 'z', 'h', 'i', 'h', 'a', 'o', ' ', 'i', 's', ' ', 'c', 'a', 'i', 'g', 'o', 'u']
>>> b[0:9]
['g', 'a', 'o', 'z', 'h', 'i', 'h', 'a', 'o']
>>> ''.join(b[0:9])
'gaozhihao'
>>> b[::-1]
['u', 'o', 'g', 'i', 'a', 'c', ' ', 's', 'i', ' ', 'o', 'a', 'h', 'i', 'h', 'z', 'o', 'a', 'g']
>>> 